The requirements and performance of compositions used for sealing rock and soil have increased in the course of time. These requirements involve both improved environmental and technical aspects. Previously, various plastics and polymers involving toxic substances have been employed to seal water leaks in e.g. concrete walls, tunnels, or cavities formed on the back side of a concrete wall. Such sealing chemicals have in a number of cases caused contamination of groundwater and health problems to e.g. construction workers handling them. However, attempts have been made to replace hazardous products with more environmentally adapted ones. New products have also been sought for to meet the recently imposed leakage restrictions. In some instances, water leakage levels below 1 liter/(min*100 meters) have been the upper threshold on constructions sites of tunnels. This have forced the suppliers to provide technically improved sealing products. U.S. Pat. No. 5,396,749 describes a method for cutting off water flow by grouting whereby troubles due to water leakage and collapse of ground is prevented. The cut-off agent is prepared by mixing e.g. colloidal silica, inorganic salt, and a water-soluble urethane polymer.
However, the strength of these agents has shown to be insufficient in several applications, particularly where the agent during injection and gelling is exposed to a high water pressure. Especially unstable agents have during the ageing phase resulted in a fairly low long term strength. Sealing agents have also been used for sealing soil to prevent leakage of contaminants in subterranean areas like buried sources, waste dumps etc. U.S. Pat. No. 5,836,390 describes a method of forming subsurface barriers where a viscous liquid comprising e.g. polybutenes, polysiloxanes, and colloidal silica is injected.
It is desirable to provide an environmentally adapted liquid cut-off agent having a high long term strength, especially in the field of sealing rock, where the cut-off agents may be subjected to high water pressure from groundwater. It is also desirable to provide durable products which resist washout forces and having a low permeability, i.e. impermeable to water and other liquids.
It is an object of the present invention to provide such products solving the drawbacks of the prior art referred to above.